Chapter # 4 Gas Diffusing Flashcards
What DLco Stand for?
Diffusion in litters of Carbon monoxide (CO2)
What DLco measures?
It measures the tranfer of Carbon Monoxide (CO) across the alveolar capillaries membranes
What combine with Hb 210 more readily than O2?
Carbon Monoxide (CO)
DLco is Expressed as:
ml of CO/minute/mm Hg (STPD)
Diffusion Capacity Procedure consist on:
- Unforced Exhalation to RV (limited to 6 seconds)
- Rapid inhalation of a diffusin gas mixture to TLC
- Breath hold at TLC for 10 +/- 2 seconds
- Rapid Exhalation (not more than 4 seconds)
- Alveolar gas is collected after a washout volume (0.75-1.0L) has been discared.
- Sample gas volume should be 0.5- 1.0L
- Sample is analyzed for the fractional CO and He concentration
True or False
Change in He concentration reflects dilution by gas in Lungs at RV !!
TRUE
And this change is used to determine the initial CO concentration
The average DLcoSb value is?
25 ml CO/min/mm Hg (STPD)
DLcoSb Patient pretest preparation, Smoking should refrain for at least…?
1 hour prior test
CO produced by cigarrete will seat on the hemoglobin saturating them, as consequence test will be not accuarete because there will be not space for the CO used on the test.
DLcoSb pretest patient preparation, Alcohol shoul stop how many hours prior test and why?
Alcohol comsuption should stop 4 hour prior exam.
Why:
Alcohol vapors can reflect the accuracy of some fuel cell types of CO analyzer
Why Steneous exercises prior DLcoSb test is not recommended ?
Because Stenous exercises will increase blood circulation into the pulmonary capillaries. forthermore more gas will be diffused
how eating just before DLcoSb test will affect the result?
Because blood will go to the digestive system whish demand more blood while digestion, as a consequense pulmonary capillari will have a decrease in the circulation afecting Gas Diffusion. ( less blood-less Hg- less Diffusion)
How long prior DLcoSb test, supplemental O2 should be discontinued?
At least 5 minutes prior test
If we do not stop Supplemental O2 prior a DLcosb test, how this will affect it?
It will slow down the afinity for Hb because both molecules O2 and CO will compete for the same Hemoglobin.
DLcoSb criteria for acceptability
- Volume-Time tracing should show smooth, rapid inspiration ( < 4sec from RV to TLC)
- Expiration should be rapid but not forced; 4 sec or less
- Dead Space washout should be 0.75 to 1.0 L (0.5L if VC is less than 2 L)
- Aleolar sample volume should be 0.5 - 1.0 L
- Inspired Volume should be at least 85% of the previous recored best VC.
- Breath hold time should be 10 sec +/-2sec
- The average of two or more cceptable test should be reported. Duplicate determintion should be within 10% of hiest value or 3 ml CO/min/mm Hg.
DLcoSb significance and pathology, what causes reduced Diffusing Capacity?
Restrictive patterns like:
- Asbestosis
- Berylliosis
- Silicosis
- Sarcoidiosis
- Sclerodrema
All these causes thicking and scaring of the long !!
True or False
DLcoSb is also called a single Breath method?
True
What Does DLcoSb?
DLcoSb measures the tranfer of CO across alveolar capillaries membrane
If the reason of DLcoSb is to measures Oxygen across the Alveolar capillarie membrane then why we used CO instead?
Because CO is 210 time more faster than Oxygen
Which Lung will diffused more gas, and SMALL or a BIG LUNG?
Big lung will diffuse more gas, because they have more surface
True Or False
DLcoSb some times is used to diffirentiate between Emphysema and Chronic Bronchitis !!!
True
DLcoSb is reduced on Emphysema patients but in chronic Bronchitis patients may be normal or redused
What will happen to a COPD patients that their DLcoSb is 50% of predicted?
Oxygen Desaturation will occur
What is DL/VA?
Is a ratio that measures Duffusion compare to lung Volume, this measure normally should be 4-5 ml CO tranfered/minutes/liter
On Obstructive Disease DL/VA ratio will be…?
DL/VA ratio will be reduced just as FEV1% on Spirometry
DL/VA ratio on Restrictive Pattern will be…?
DL/VA ratio will be preserved
How DLcoSb could be affected?
- Hemoglibin ( low Hb reduces DLco, High Hb elevates DLco)
- Carboxyhemoglobin [(COHb), High COHb reduces DLco]
- Alveolar PCO2 ( high PCO2 mean not room for O2)
- Pulmonary Capillary blood volume ( muller maneuver increased cardiac output increased DLco, Valsalva maneuver decreased DLco )
- Altitud above sea level (high altitud increses DLco)
- Poor inspiratory effort during testing ( If less than 85% of VC will decreased DLco)
True Or False
On DLcoSb criteria for acceptability, Volume time tracing should be smooth, rapid inspiration (<4sec) from RV to TLC?
TRUE
TRUE or FALSE
On DLcoSb criteria for acceptability Expiration should be rapid but not forced; 4 sec or less?
TRUE
TRUE or FALSE
Dead Space should be 0.75-1.0 L (0.5L if VC is less than 2L)
DLcoSb criteria for acceptability?
TRUE
On criteria for acceptability, inspired volume should be at least:
- A. 50% of VC
- B. 100% of VC
- C. 85% OF VC
C. 85% of VC
TRUE or False
Unforced Exhalation to RV (limited to 6 sec)
is part of DLcoSb precedure?
TRUE
In which of the following conditions would an increased DLco be expected?
- Pulmonary Hemorrhage
- Sarcoidosis
- Pneumonectomy
* 4. Polycythemia
- Pneumonectomy
1 and 4
Pulmonary Hemorrhage and Polycythemia
High altitud above sea level will increase or decrease DLcoSb?
Increase
